Rutin and barley starch modification using subcritical water, ultrasonication and electrolysis technologies

• Author / Creator

  Ekaette, Idaresit

• The barley grain is a rich source of starch and dietary fibre but over the years, barley grain uses in Canada has been more popular in animal feeding and brewing, than for food uses. With the large barley production and increasing demand for starch by the food and biobased industries, barley starch has become an item of economic value. Therefore, the objective of this research was to isolate barley starch and modify the barley starch properties for suitability in functional food applications. Towards the development of a functional ingredient, rutin, a flavonoid compound was selected to be added to the isolated barley starch. The incorporation of rutin into the barley starch matrix was enhanced by thermal treatments using subcritical water, ultrasonication and electrolysis technologies. In the first study, barley starch (0%, 22%, 37% amylose) with rutin treated at 80 oC and subcritical water temperatures of 100-160 oC/7 MPa/30 min resulted in the addition of 0.19-0.87 mg rutin/g starch dry matter. Comparison of barley starches with and without rutin showed a loss of amylose, for the 37% amylose starch at 100 oC, and 22% amylose starch at 120 oC, indicating that rutin was involved in V-amylose inclusion complexation. The 37% amylose starch with 0.34 mg rutin/g starch dry matter had the highest observed expansion (specific volume) of 6.10 ± 0.12 mL/g at 160 oC; a 392% increase from 1.24±0.01 mL/g of native 37% amylose starch at room temperature (23 oC). In the second study, ultrasonication treatment at energy density (3.6-36 kJ/mL, 47 oC) and change in energy density (0.1-7.0 kJ/mL, 86 oC) was carried out on rutin hydrate in water, 0.01 g/mL citric acid, and 0.01 g/mL sodium chloride. The highest increase in total flavonoid content of 74% was observed in the water media (27 kJ/mL). Quercetin, an aglycone of rutin was produced (with treatment in the citric acid media) as change in energy density increased from 0.1 kJ/mL (0.34±0.09%) to 7.0 kJ/mL (2.23±0.04%). In the third study, further characterization on the recrystallized rutin after ultrasonication (insoluble fraction) showed long, and slender strands of rutin nanocrystals (100-820 nm) bound as agglomerates (SEM images). According to DSC endotherms, new rutin polymorphs were formed with all solvent treatments at 3.9 kJ/mL, and 7.0 kJ/mL, and with water, 36 kJ/mL. The new rutin polymorphs used in pyrodextrinization (2.2 M HCl, 90 oC, 1 h) of barley starch did not significantly change the quantity of malto-oligosaccharides (DP 1-7) produced from the control barley starch (without rutin). In the final study, waxy barley flour (0% amylose content) slurry (1:6 w/w in water) was treated by electrolysis at voltages of 5-30 V, and electrode length of 4-8 cm. Starches isolated from the electrolysed barley flour slurry had higher metal content (magnesium 2.9% and phosphorus 13.0%) compared to magnesium 0.8% and phosphorus 3.5% of the alkali-treated starch (starch isolated by conventional method). The electrolysed freeze-dried starch gel had a high absorption capacity in water as 1659±24%, observed for treatment at 15 V, and 8 cm. However, the effect of rutin addition in the freeze-dried starch gels inhibited rehydration. All electrolysed starch gels with and without rutin were opaque and exhibited no change of firmness at 40 days of storage at room temperature. The structural behavior of the electrolysed starches was related to enhanced crystallinity by electrolysis (FT-IR results). Based on the technologies and thermal treatments utilized, modified barley starches loaded with rutin have been produced with the unique characteristics of expanded starch (lighter mass per volume), dextrin (as a soluble starch), and opaque superabsorbent hydrogels (to enhance light protection of rutin). These starches can find applications in functional foods, cosmetics, and the pharmaceutical industry.

• Subjects / Keywords

  • Rutin
  • Starch complexation
  • Flavonoid
  • Functional food
  • Emerging technologies
  • Pressurized fluid
  • Barley processing

• Graduation date

  Spring 2020

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-7pzy-ma40

• License

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